Asteroid Deflection by Leveraging Rotational Self-Energy

Abstract

A novel concept for the deflection of rotating asteroids is presented, based on the conversion of the asteroid rotational kinetic energy into translational kinetic energy. Such conversion is achieved using an orbital siphon, a tether-connected chain of masses, arranged vertically from the asteroid surface, which exploits the rotation of the asteroid for the delivery of mass from the asteroid to escape. Under the conditions to be discussed, the siphon can be initiated to ensure self-sustained flow of mass from the asteroid to escape. This mechanism is proposed to use a fraction of the asteroid as reaction mass, with the asteroid rotational kinetic energy leveraged to deliver the mass to escape and hence impart a reaction on the asteroid itself. Key parameters, such as velocity change, deflection duration, tension requirements and siphon length, are discussed. Deflection e ectiveness is assessed for di erent release strategies. It is shown that typical velocity changes on the order of 1 cm s 1 can be achieved within a time window of a decade.

Excavation of artificial caverns inside asteroids by leveraging rotational self-energy

“…It was shown by Viale et al (2018a) that the momentum exchange between the mass to be connected to the chain and the rest of the chain induces a deceleration of the siphon which eventually causes the siphon to reach a bound steady state velocity. For a siphon modelled as continuous mass distribution, the steady state velocity can be expressed in non-dimensional form as in Viale et al (2020b)…”

“…The total time required to extract the mass ̄ is related to the siphon radial velocity and siphon linear density ̄ via Viale et al (2020b): for a siphon modelled as a continuous mass distribution. Similarly, the instantaneous mass rate of material lifted by the siphon is (Viale et al, 2020b):…”

“…The material removed from the asteroid may also be used as reaction mass to change the asteroid orbit. This can be achieved either via mass drivers (Dunn, Fagin, Snyder and Joyce, 2017) or tethered systems (Viale, McInnes, Bailet and Ceriotti, 2020b). More speculatively, the internal cavity may be pressurised to facilitate the disruption of the asteroid.…”